| // Copyright 2014 The Chromium Authors |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "base/big_endian.h" |
| |
| #include <string.h> |
| |
| #include "base/numerics/byte_conversions.h" |
| #include "base/numerics/checked_math.h" |
| #include "base/strings/string_piece.h" |
| |
| namespace base { |
| |
| BigEndianReader BigEndianReader::FromStringPiece( |
| base::StringPiece string_piece) { |
| return BigEndianReader(base::as_byte_span(string_piece)); |
| } |
| |
| BigEndianReader::BigEndianReader(const uint8_t* buf, size_t len) |
| : // TODO(crbug.com/40284755): Remove this constructor entirely, callers |
| // should use span constructor. |
| UNSAFE_BUFFERS(buffer_(buf, len)) {} |
| |
| BigEndianReader::BigEndianReader(base::span<const uint8_t> buffer) |
| : buffer_(buffer) {} |
| |
| BigEndianReader::~BigEndianReader() = default; |
| |
| bool BigEndianReader::Skip(size_t len) { |
| if (len > remaining()) { |
| return false; |
| } |
| buffer_ = buffer_.subspan(len); |
| return true; |
| } |
| |
| bool BigEndianReader::ReadBytes(void* out, size_t len) { |
| std::optional<span<const uint8_t>> o = ReadSpan(len); |
| if (o.has_value()) { |
| memcpy(out, o->data(), o->size_bytes()); |
| return true; |
| } |
| return false; |
| } |
| |
| bool BigEndianReader::ReadPiece(base::StringPiece* out, size_t len) { |
| if (len > remaining()) { |
| return false; |
| } |
| auto [view, remain] = buffer_.split_at(len); |
| *out = base::StringPiece(reinterpret_cast<const char*>(view.data()), |
| view.size()); |
| buffer_ = remain; |
| return true; |
| } |
| |
| std::optional<span<const uint8_t>> BigEndianReader::ReadSpan( |
| base::StrictNumeric<size_t> n) { |
| if (remaining() < size_t{n}) { |
| return std::nullopt; |
| } |
| auto [consume, remain] = buffer_.split_at(n); |
| buffer_ = remain; |
| return {consume}; |
| } |
| |
| bool BigEndianReader::ReadU8(uint8_t* value) { |
| std::optional<span<const uint8_t, 1u>> bytes = ReadFixedSpan<1u>(); |
| if (!bytes.has_value()) { |
| return false; |
| } |
| *value = numerics::U8FromBigEndian(*bytes); |
| return true; |
| } |
| |
| bool BigEndianReader::ReadU16(uint16_t* value) { |
| std::optional<span<const uint8_t, 2u>> bytes = ReadFixedSpan<2u>(); |
| if (!bytes.has_value()) { |
| return false; |
| } |
| *value = numerics::U16FromBigEndian(*bytes); |
| return true; |
| } |
| |
| bool BigEndianReader::ReadU32(uint32_t* value) { |
| std::optional<span<const uint8_t, 4u>> bytes = ReadFixedSpan<4u>(); |
| if (!bytes.has_value()) { |
| return false; |
| } |
| *value = numerics::U32FromBigEndian(*bytes); |
| return true; |
| } |
| |
| bool BigEndianReader::ReadU64(uint64_t* value) { |
| std::optional<span<const uint8_t, 8u>> bytes = ReadFixedSpan<8u>(); |
| if (!bytes.has_value()) { |
| return false; |
| } |
| *value = numerics::U64FromBigEndian(*bytes); |
| return true; |
| } |
| |
| bool BigEndianReader::ReadU8LengthPrefixed(std::string_view* out) { |
| span<const uint8_t> rollback = buffer_; |
| uint8_t len; |
| if (!ReadU8(&len)) { |
| return false; |
| } |
| const bool ok = ReadPiece(out, len); |
| if (!ok) { |
| buffer_ = rollback; // Undo the ReadU8. |
| } |
| return ok; |
| } |
| |
| bool BigEndianReader::ReadU16LengthPrefixed(std::string_view* out) { |
| span<const uint8_t> rollback = buffer_; |
| uint16_t len; |
| if (!ReadU16(&len)) { |
| return false; |
| } |
| const bool ok = ReadPiece(out, len); |
| if (!ok) { |
| buffer_ = rollback; // Undo the ReadU8. |
| } |
| return ok; |
| } |
| |
| BigEndianWriter::BigEndianWriter(span<uint8_t> buffer) : buffer_(buffer) {} |
| |
| BigEndianWriter::BigEndianWriter(char* buf, size_t len) |
| : // TODO(crbug.com/40284755): Remove this constructor entirely, callers |
| // should use span constructor. |
| UNSAFE_BUFFERS(buffer_(reinterpret_cast<uint8_t*>(buf), len)) {} |
| |
| BigEndianWriter::~BigEndianWriter() = default; |
| |
| bool BigEndianWriter::Skip(size_t len) { |
| if (len > remaining()) { |
| return false; |
| } |
| buffer_ = buffer_.subspan(len); |
| return true; |
| } |
| |
| bool BigEndianWriter::WriteBytes(const void* buf, size_t len) { |
| return WriteSpan( |
| // TODO(crbug.com/40284755): Remove WriteBytes() entirely, callers |
| // should use WriteSpan().. |
| UNSAFE_BUFFERS((base::span(static_cast<const uint8_t*>(buf), len)))); |
| } |
| |
| bool BigEndianWriter::WriteSpan(base::span<const uint8_t> bytes) { |
| if (remaining() < bytes.size()) { |
| return false; |
| } |
| auto [write, remain] = buffer_.split_at(bytes.size()); |
| write.copy_from(bytes); |
| buffer_ = remain; |
| return true; |
| } |
| |
| bool BigEndianWriter::WriteU8(uint8_t value) { |
| // TODO(danakj) this span constructor should be implicit. |
| return WriteFixedSpan(base::span(numerics::U8ToBigEndian(value))); |
| } |
| |
| bool BigEndianWriter::WriteU16(uint16_t value) { |
| // TODO(danakj) this span constructor should be implicit. |
| return WriteFixedSpan(base::span(numerics::U16ToBigEndian(value))); |
| } |
| |
| bool BigEndianWriter::WriteU32(uint32_t value) { |
| // TODO(danakj) this span constructor should be implicit. |
| return WriteFixedSpan(base::span(numerics::U32ToBigEndian(value))); |
| } |
| |
| bool BigEndianWriter::WriteU64(uint64_t value) { |
| // TODO(danakj) this span constructor should be implicit. |
| return WriteFixedSpan(base::span(numerics::U64ToBigEndian(value))); |
| } |
| |
| } // namespace base |